The Return of Suppressed Thoughts in Dreams

People spent 5 min before sleep at home writing their stream of thought as they suppressed thoughts of a target person, thought of the person, or wrote freely after mentioning the person. These presleep references generally prompted people to report increased dreaming about the person. However, suppression instructions were particularly likely to have this influence, increasing dreaming about the person as measured both by participants’ self-ratings of their dreams and by raters’ coding of mentions of the person in written dream reports. This effect was observed regardless of emotional attraction to the person. Wishes suppressed during the day assert themselves in dreams. —Freud (1900/1965, p. 590) Freud’s account of dreams is one of the most well known psychological theories. Most of us have heard a lecture—or given one—on dreams as the ‘‘royal road to the unconscious,’’ and through sheer familiarity we may have come to believe that thoughts avoided in waking return in dreams. Yet the logic of this theory is also famously complicated— involving repression, psychic wish fulfillment, interpretations of latent content, and more—leaving Freud’s version largely untested (Erdelyi, 1985; Hobson, 1988). The present study tested an uncomplicated version of the idea: that thoughts that are suppressed in waking will recur in dreams. Thoughts suppressed in waking do tend to return in waking. People asked to suppress an otherwise unremarkable thought have difficulty doing so, and show a subsequent rebound of that thought in selfreports of thinking (Wegner, Schneider, Carter, & White, 1987; Wenzlaff & Wegner, 2000). The suppressed thought ‘‘pops’’ to mind in intrusive recurrences, and measures of automatic activation show that the levels of accessibility induced by suppression even exceed those prompted by intentional concentration (Wegner & Erber, 1992; Wenzlaff & Bates, 2000). This hyperaccessibility of suppressed thoughts in waking has been explained in terms of the theory of ironic processes of mental control (Wegner, 1994). In this view, intentional control of mental states is accomplished through the interaction of two processes—(a) a conscious and effortful operating process that attempts to create the desired mental state by searching for contents consistent with that state and (b) an unconscious and automatic ironic process that searches for mental contents indicating failure of control. For someone trying not to think about eating chocolate cake, for example, the operating process might involve effortful attempts to think of dieting, cholesterol, obesity, or, in fact, anything other than chocolate cake. The monitoring process, however, would search automatically for forbidden thoughts of chocolate cake. Suppressed thoughts become more accessible under mental load because load undermines the operating process while allowing the ironic process to continue unimpeded (Wenzlaff & Wegner, 2000). The automatic search for failures in mental control may, under conditions of mental load, function to create such failures. Ironic-process theory suggests that suppressed thoughts might recur in dreams more than would other presleep waking thoughts. This inference follows from evidence that dream states (marked by periods of rapid eye movement, or REM) are accompanied by deactivation of areas of the prefrontal cortex that underlie executive and working memory functions in waking (Braun et al., 1997; Hobson, Pace-Schott, & Stickgold, 2000; Muzur, Pace-Schott, & Hobson, 2002). Such prefrontal areas could play a role in supporting the mental-control operating process (Mitchell, Heatherton, Kelley, Wyland, & Macrae, 2003). Their deactivation could allow greater influence by ironic processes, and hence, lead to increased accessibility of suppressed thoughts in dreams. So, although dreams sometimes contain ‘‘day residue’’—direct echoes of prior waking experience (e.g., Cohen, 1972; Hartmann, 1968; Stickgold, Malia, Maguire, Roddenberry, & O’Connor, 2000)—they might be yet more likely to include residue of thoughts that have been intentionally suppressed. Indirect evidence for the dream rebound of suppressed thoughts comes from dreams people report after experiences that naturally prompt thought suppression. People often suppress thoughts of traumatic events, for example, and such events are often reflected in dreams (Mellman, David, Bustamante, Torres, & Fins, 2001). Similarly, thought suppression is a common strategy for self-control, and people engaged in self-control often have dreams of the controlled item. Abstaining smokers report dreams of smoking (Hajek & Belcher, 1991), and crack-cocaine users report dreaming of drug use during abstinence as well (Reid & Simeon, 2001). Emotional thoughts might also prompt suppression, so the abundance of emotional thought in dreams (Neilson, Deslauriers, & Baylor, 1991; Revonsuo, 2000) could be interpreted as supporting the idea Address correspondence to Daniel M. Wegner, Department of Psychology, Harvard University, 33 Kirkland St., WJH 1470, Cambridge, MA 02138; e-mail: [email protected]. PSYCHOLOGICAL SCIENCE 232 Volume 15—Number 4 Copyright r 2004 American Psychological Society that suppressed thoughts rebound in dreams. Topics of thought that return frequently to mind and that are associated with emotional experience have been called ‘‘current concerns’’ (Nikula, Klinger, & Larson-Gutman, 1993)—and these recur in dreams and are easily prompted in dreams by presleep suggestions (Nikles, Brecht, Klinger, & Bursell, 1998; Saredi, Baylor, Meier, & Strauch, 1997). The evidence for a role of prior suppression in dreams remains indirect, however, because of the natural confounding of emotion and spontaneous suppression. We cannot be certain that it is suppression, and not emotion, that prompts the dream return of emotional thoughts, even though emotional thoughts may have been spontaneously suppressed, because emotion and suppression regularly co-occur. To disentangle these influences, this study tested whether instructed thought suppression (Wegner, 1989; Wenzlaff & Wegner, 2000) would orient dream content to the suppressed thought regardless of whether the thought was emotionally charged. Participants nominated an emotional thought (of a ‘‘crush,’’ someone to whom they were romantically attracted) and an unemotional thought (a ‘‘noncrush,’’ someone to whom they were not attracted; cf. Wegner & Gold, 1995). Participants then engaged in one of three presleep thought exercises directed toward one of the targets: trying not to think about the target (suppression), thinking about the target (expression), or thinking about anything at all after noting the target’s identity (mention). Expression was included to allow examination of the influence of focused presleep attention to the target, as in prior studies (e.g., Saredi et al., 1997). Mentioning was included as a comparison condition for examining the influence of minimal content priming of the thought without any intentional mental control (Wenzlaff & Wegner, 2000). Dream reports and ratings collected the next morning were examined for indications of thoughts about each target.